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	<div id="pagetitle"><h1>YUI Library Examples: IO: Cross-Domain JSON Transaction &mdash; Retrieving a News Feed from Yahoo! Pipes</h1></div>
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	<div id="bar-note"><p><strong>Note:</strong> This is YUI 3.x. Looking for <a href="http://developer.yahoo.com/yui/">YUI 2.x</a>?</p></div>

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	<h2>IO: Cross-Domain JSON Transaction &mdash; Retrieving a News Feed from Yahoo! Pipes</h2>

	<div id="example" class="promo">
	<p>
	<p>In the example below, IO is employed to make a cross-domain request to <a href="http://pipes.yahoo.com">Yahoo! Pipes</a>.  The output of the Pipe is an RSS-style feed formatted as JSON.  We pass that output to the JSON Utility's <code>parse</code> method for sanitization and then display the contents of the Pipe in a list.</p>

<p>The cross-domain approach obviates the need for a server-side proxy, making it faster. And the use of IO in place of a script node allows us to retrieve the JSON data as a string and execute <code>JSON.parse</code> against it, making it safer to use; a script node would evaluate immediately in the global scope as soon as it was loaded.</p>	</p>	

	<div class="module example-container ">
			<div class="hd exampleHd">
			<p class="newWindowButton yui-skin-sam">
                <a href="io-xdr_clean.html" target="_blank">View example in new window.</a>
            </p>
		</div>		<div id="example-canvas" class="bd">

		
	<!--BEGIN SOURCE CODE FOR EXAMPLE =============================== -->
	
	<button id="fetch" disabled="disabled">Load JSON RSS news feed from Yahoo! Pipes.</button>

<div id="output">
	<ul>
		<li>Content from Yahoo! Pipes feed will display here.</li>
    </ul>
</div>

<script language="javascript">

YUI({base:"../../build/", timeout: 10000}).use("io", "substitute", "json-parse",

	function(Y) {

		//Data fetched will be displayed in a UL in the
		//element #output:
		var output = Y.Node.get("#output ul");

		//Configure the cross-domain protocol:
		var xdrConfig = {
			id:'flash', //We'll reference this id in the xdr configuration of our transaction.
			yid: Y.id,  //The yid provides a link from the Flash-based XDR engine
						//and the YUI instance.
			src:'../../build/io/io.swf?t=' + new Date().valueOf().toString() //Relative path to the .swf file from the current page.
		};
		Y.io.transport(xdrConfig);

		//Event handler called when the transaction begins:
		var handleStart = function(id, a) {
			Y.log("io:start firing.", "info", "example");
			output.set("innerHTML", "<li>Loading news stories via Yahoo! Pipes feed...</li>");
		}

		//Event handler for the success event -- use this handler to write the fetched
		//RSS items to the page.
		var handleSuccess = function(id, o, a) {

			//We use JSON.parse to sanitize the JSON (as opposed to simply eval'ing
			//it into the page):
			var oRSS = Y.JSON.parse(o.responseText);

			//From here, we simply access the JSON data from where it's provided
			//in the Yahoo! Pipes output:
			if (oRSS && oRSS.count) {

				var s = "<!--begin news stories fetched via Yahoo! Pipes-->",
					//t in this case is our simple template; this is fed to
					//Y.Lang.substitute as we loop through RSS items:
					t = "<li><a href='{link}'>{title}</a>, {pubDate}</li>";

				for (var i=0; i<oRSS.count; i++) {
					s += Y.Lang.substitute(t, oRSS.value.items[i]);
				}

				//Output the string to the page:
				output.set("innerHTML", s);
				output.addClass("yui-null");

			} else {
				//No news stories were found in the feed.
				var s = "<li>The RSS feed did not return any items.</li>";
			}
		}

		//In the event that the HTTP status returned is > 399, a
		//failure is reported and this function is called:
		var handleFailure = function(id, o, a) {
			Y.log("ERROR " + id + " " + a, "info", "example");
		}

		//With all the aparatus in place, we can now configure our
		//io call.
		var cfg = {
			method: "GET",
			xdr: {
				use:'flash' //This is the xdrConfig id we referenced above.
			},
			on: {
				//Our event handlers previously defined:
				start: handleStart,
				success: handleSuccess,
				failure: handleFailure
			}
		};

		//Wire the buttton to a click handler to fire our request each
		//time the button is clicked:
		var handleClick = function(o) {
			Y.log("Click detected; beginning io request to Yahoo! Pipes.", "info", "example");
			var obj = Y.io(
				//this is a specific Pipes feed, populated with cycling news:
				"http://pipes.yahooapis.com/pipes/pipe.run?_id=giWz8Vc33BG6rQEQo_NLYQ&_render=json",
				cfg
			);
		}

		//add the clickHandler as soon as the xdr Flash module has
		//loaded:
		Y.on('io:xdrReady', function() {
			var fetch = Y.Node.get("#fetch");
			fetch.set("disabled", false);
			Y.on("click", handleClick, fetch);
		});

	}
);
</script>	
	<!--END SOURCE CODE FOR EXAMPLE =============================== -->
	
		
		</div>
	</div>			
	</div>
		
	<h2 class="first">Implementing a Simple Cross-Domain Request for JSON Data</h2>

<p>In this example, we begin with a YUI instance that loads the IO and JSON modules:</p>

<textarea name="code" class="JScript" cols="60" rows="1">
//Create a YUI instance including support for IO and JSON modules:
YUI({base:"../../build/", timeout: 10000}).use("io-xdr", "substitute", "json-parse", function(Y) {
	// Y is the YUI instance.
	// The rest of the following code is encapsulated in this
	// anonymous function.
} );
</textarea>
<p>We'll also get a Node reference to the container we'll be using to output the data we retrieve:</p>

<textarea name="code" class="JScript" cols="60" rows="1">//Data fetched will be displayed in a UL in the
//element #output:
var output = Y.Node.get("#output ul");</textarea>

<p>Next, we configure IO's cross-domain interface for this YUI instance.  Flash is the underlying mechansim used here.  Be sure to configure the <code>src</code> property to point to your <code>IO.swf</code> file.</p>

<textarea name="code" class="JScript" cols="60" rows="1">//Configure the cross-domain protocol:
var xdrConfig = {
    id:'flash', //We'll reference this id in the xdr configuration of our transaction.
    yid: Y.id,  //The yid provides a link from the Flash-based XDR engine
                //and the YUI instance.
    src:'../../build/io/IO.swf?t=' + new Date().valueOf().toString() //Relative path to the .swf file from the current page.
};
Y.io.transport(xdrConfig);</textarea>

<p>The configuration for our specific IO transaction contains a reference to the <code>xdr</code> configuration we created above and specifies that there will not be a need to process the response as XML (we're getting JSON instead):</p>

<textarea name="code" class="JScript" cols="60" rows="1">var cfg = {
    method: "GET",
    xdr: {
        use:'flash', //This is the xdrConfig id we referenced above.
        responseXML:false //we're using JSON -- marginally faster, and
                          //supported by the Pipes API
    },
    on: {
        //Our event handlers previously defined:
        start: handleStart,
        success: handleSuccess,
        failure: handleFailure
    }
};</textarea>

<p>The final step is to make the request:</p>

<textarea name="code" class="JScript" cols="60" rows="1">var obj = Y.io(
    //this is a specific Pipes feed, populated with cycling news:
    "http://pipes.yahooapis.com/pipes/pipe.run?_id=giWz8Vc33BG6rQEQo_NLYQ&_render=json",
    cfg
);</textarea>

<h3>Full Script</h3>

<p>The full script source for this example is as follows:</p>

<textarea name="code" class="JScript" cols="60" rows="1">
YUI({base:"../../build/", timeout: 10000}).use("io-xdr", "substitute", "json-parse",

	function(Y) {

		//Data fetched will be displayed in a UL in the
		//element #output:
		var output = Y.Node.get("#output ul");

		//Configure the cross-domain protocol:
		var xdrConfig = {
			id:'flash', //We'll reference this id in the xdr configuration of our transaction.
			yid: Y.id,  //The yid provides a link from the Flash-based XDR engine
						//and the YUI instance.
			src:'../../build/io/IO.swf' //Relative path to the .swf file from the current page.
		};
		Y.io.transport(xdrConfig);

		//Event handler called when the transaction begins:
		var handleStart = function(id, a) {
			Y.log("io:start firing.", "info", "example");
			output.set("innerHTML", "<li>Loading news stories via Yahoo! Pipes feed...</li>");
		}

		//Event handler for the success event -- use this handler to write the fetched
		//RSS items to the page.
		var handleSuccess = function(id, o, a) {

			//We use JSON.parse to sanitize the JSON (as opposed to simply eval'ing
			//it into the page):
			var oRSS = Y.JSON.parse(o.responseText);

			//From here, we simply access the JSON data from where it's provided
			//in the Yahoo! Pipes output:
			if (oRSS && oRSS.count) {

				var s = "<!--begin news stories fetched via Yahoo! Pipes-->",
					//t in this case is our simple template; this is fed to
					//Y.Lang.substitute as we loop through RSS items:
					t = "<li><a href='{link}'>{title}</a>, {pubDate}</li>";

				for (var i=0; i<oRSS.count; i++) {
					s += Y.Lang.substitute(t, oRSS.value.items[i]);
				}

				//Output the string to the page:
				output.set("innerHTML", s);

			} else {
				//No news stories were found in the feed.
				var s = "<li>The RSS feed did not return any items.</li>";
			}
		}

		//In the event that the HTTP status returned is > 399, a
		//failure is reported and this function is called:
		var handleFailure = function(id, o, a) {
			Y.log("ERROR " + id + " " + a, "info", "example");
		}

		//With all the aparatus in place, we can now configure our
		//io call.
		var cfg = {
			method: "GET",
			xdr: {
				use:'flash', //This is the xdrConfig id we referenced above.
				responseXML:false //we're using JSON -- marginally faster, and
								  //supported by the Pipes API
			},
			on: {
				//Our event handlers previously defined:
				start: handleStart,
				success: handleSuccess,
				failure: handleFailure
			}
		};

		//Wire the buttton to a click handler to fire our request each
		//time the button is clicked:
		var handleClick = function(o) {
			Y.log("Click detected; beginning io request to Yahoo! Pipes.", "info", "example");
			var obj = Y.io(
				//this is a specific Pipes feed, populated with cycling news:
				"http://pipes.yahooapis.com/pipes/pipe.run?_id=giWz8Vc33BG6rQEQo_NLYQ&_render=json",
				cfg
			);
		}

		//add the clickHandler as soon as the xdr Flash module has
		//loaded:
		Y.on('io:xdrReady', function() {
			var fetch = Y.Node.get("#fetch");
			fetch.set("disabled", false);
			Y.on("click", handleClick, fetch);
		});
	}
);
</textarea>				</div>
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					<div id="examples" class="mod box4">
                        <div class="hd">
						<h4>
    IO Examples:</h4>
                        </div>
						<div class="bd">
							<ul>
								<li><a href='../io/io-get.html'>GET Transaction</a></li><li><a href='../io/io-post.html'>POST Transaction</a></li><li><a href='../io/io-weather.html'>XML Transaction &mdash; Retrieving a Yahoo! Weather RSS (XML) Feed via a Server-Side Proxy</a></li><li class='selected'><a href='../io/io-xdr.html'>Cross-Domain JSON Transaction &mdash; Retrieving a News Feed from Yahoo! Pipes</a></li><li><a href='../node-menunav/node-menunav-8.html'>Adding Submenus On The Fly (included with examples for MenuNav Node Plugin)</a></li><li><a href='../overlay/overlay-io-plugin.html'>IO Plugin (included with examples for Overlay)</a></li><li><a href='../dd/portal-drag.html'>Portal Style Example (included with examples for Drag &amp; Drop)</a></li>							</ul>
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						<h4>More IO Resources:</h4>
                        </div>
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						<ul>
							<!-- <li><a href="http://developer.yahoo.com/yui/io/">User's Guide</a> (external)</li> -->
						<li><a href="../../api/module_io.html">API Documentation</a></li>
</ul>
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